Investigation of MAGSAT and TRIAD magnetometer data to provide corrective information on high-lattitude external fields

Abstract

Disturbances in the MAGSAT magnetometer data set due to high latitude phenomena were evaluated. Much of the categorization of disturbances due to Birkeland currents, ionospheric Hall currents, fine structure and wave phenomena was done with the MAGSAT data catalog. A color graphics technique was developed for the display of disturbances from multiple orbits, from which one can infer a 'global-image' of the current systems of the auroral zone. The MAGSAT 4/81 magnetic field model appears to represent the Earth's main field at high latitudes very well for the epoch 1980. MAGSAT's low altitude allows analysis of disturbances in the magnetometer data due to ionospheric electrojet currents. These current distributions were modeled properly for single events as a precursor to the inference of the Birkeland current system. MAGSAT's orbit was approximately shared with that of the Navy/APL TRIAD satellite. This allowed space-time studies of the magnetic disturbance signatures to be performed, the result being an approximately 75% agreement in, as well as high frequency of, signatures due to Birkeland currents. Thus the field-aligned currents are a steady-state participant in the Earth's magnetospheric current system